Urinary System Flashcards
Describe the overview of urinary system.
1) kidney (capsule, cortex, medulla, pelvis, interstitium)
-excrete nitrogenous waste
-conserve body fluids & electrolytes
-reabsorb solutes & water
2) ureter
-urine to bladder
3) urinary bladder
-store urine
4)urethra
-expel urine
What are the functions of the kidneys?
1) water & electrolyte homeostasis
-filtration of cellular waste from blood
-selective reabsorbtion of water & solutes
-regulation of fluid balance
-maintain electrolyte homeostatic/ acid base balance
2)excretion of metabolic waste products, bio active substances (drugs) & excess water
3) production of hormones: renin & erythropoietin
4) regulation of BP
-juxtaglomerular apparatus
5) activation of Vit D
Describe abnormal urine.
1) content
-glucose, blood, haemoglobin, myoglobin, bacteria, cells
2) color
-haemoglobin, myoglobin, bilirubin
3) volume
-polyuria, oliguria, anuria
Describe primary renal diseases.
according to site of injury
-glomeruli
-tubules
-blood vessels
-ascending infections
-renal neoplasia
-renal infarction
-renal failure
Describe the structure of the kidney.
-capsule
-renal lobe/pyramid
-outer cortex
-inner medulla
-papillae/crest
-calices (dilation of renal pelvis)
-pelvis (dilation of proximal ureter)
What are the 3 types of kidney lobes?
1) unilobar = carnivores (pyramid)
2) multilobar = ruminants (segmented)
3) multilobar = pig (smooth surface)
Describe the important tissues of the kidney.
1) capsule
-collagen
-smooth muscle
-blood vessels
2) cortex
-renal corpuscles (nephron)
-convoluted tubule (nephron)
3) medulla
-loop of Henle (nephron)
-collecting duct
4) pelvis
-urothelium
-submucosa
-smooth muscle
-adventitia
Describe the nephron.
-functional unit
-site of osmoregulation via:
-filtration of water & sm molecules from blood plasma to form a filtrate
-selective reabsorption of most of the water and other molecules
Describe the important structures in the cortex of the kidney.
-renal corpuscles
-proximal tubule (microvilli)
-distal convoluted tubules (cuboidal)
-collecting tubules
-peritubular capillary plexus
Describe the important structures of the medulla in the kidney.
-loops of henle
-collecting ducts
-vasa recta
Describe the glomerus.
Loops of capillaries with fenestrated endothelium in bowman’s capsule.
*mesangial cells between capillaries *
Describe bowman’s capsule.
-visceral epithelium = podocyte
-glomerular basement membrane
-urinary space
-parietal epithelium = squamous cells
-vascular pole
-urinary (tubular) pole
Describe the vascular pole (ultrafiltration of glomerus).
-blood enters the glomerular capillaries via afferent arteriole
-blood exits at efferent arteriole
Describe ultrafiltration at the glomerus.
-blood pushes through filtration barrier
>fenestrated endothelium
>glomerular BM
>podocyte foot processes
-ultrafiltrate enters urinary space
Describe the urinary pole (ultrafiltration at the glomerulus).
-ultrafiltrate enters proximal convoluted tubule
What are the 3 components of the filtration barrier?
located in cortex = glomerus
1. Endothelium of glomerular capillary loops with fenestrated NS
2. Glomerular BM = fused basal laminae of capillaries & podocyte
3. Podocyte with pedicels (foot processes)
*outcome = albumin & lg molecules retained. Sm molecule cross freely with ultrafiltrate.
What molecules are in filtrates?
-water
-glucose
-amino acids
-ions
-urea
-hormones
-vitamins B & C
-ketones
-protein
Describe the formation of urine.
- Primary/glomerular filtrate = produced by ultrafiltration of blood in renal corpuscles
- Ultrafiltrate similar to blood plasma (doesn’t contain most protein)
- Reabsorption of most substances (98% of filtrate reabsorbed)
-water & Na
-glucose & amino acids - Tubular secretion: K, H, NH4, bile salts, drug metabolites
- Waste molecules + some water stay in tubular system & empty into the ureter.
Describe mesangial cells.
-phagocytic
-contractile
-support
-mesangial cells + matrix = mesangium
What happens if you don’t have a glomerus?
-renal tubule is surrounded by a renal portal system & forms primitive urine by tubular secretion
Describe the 3 renal tubules.
- Proximal tubule
- Thin descending & thick ascending limb of nephron (henles) loop
- Distal convoluted tubule
Describe the proximal convoluted tubule.
-begin at urinary pole
-only in cortex
-cuboidal with microvilli = brush border
-BM
-metabolically active with mitochondria
>na/k pump
>aquaporin
>peroxisomes
-endosomes
-lysosomes
-reabsorb glucose, na/H2O, amino acids, peptides & low molecular weight proteins
What are the important aspects of Proximal Tubules?
-reabsorb anions, cations, urea
-active & absorb Na & water from glomerular filtrate in the PCT + glucose & amino acids
-activate Vit D
Describe PCT & DCT components.
- Microvilli (PCT only)
- Basal striation = folds of PM with ATP driven Na pump both in PCT and in DCT
- Mitochondria = provide ATP for Na+ pump
Describe the loop of henle (nephron loop).
-continues from PCT
-Thick descending: cuboidal
-thin: squamous (T)
-thick ascending: cuboidal (A)
-in medulla only
Longitudinal picture of loop of henle.
V= vasa recta
capillary loop that parallels nephron loops. Helps with ion & water exchange.
Describe distal convoluted tubule.
-continues from thick ascending loop of henle
-cuboidal
-no microvilli or BB
-cortex only
-site of action = aldosterone
-specialized chemoreceptor of macula densa
Renal cortex with renal corpuscle.
Renal cortex with tubules.
Describe collecting ducts.
-connect distal convoluted tubule to renal papillae/crest
-lumen = primitive urine
-cuboidal
-site of action = anti diuretic hormone via aquaporin receptors
*ex: vasopressin secreted by neurons in hypothalamus = reabsorbs solute free water & returns to circulation
-not part of nephron
Longitudinal section of collecting ducts.
-principle cells = reabsorb Na & water
-intercalated cells participate in acid base balance
Describe papillary ducts (renal papillae of canine).
-terminal portion of collecting ducts
-empty at area cribrosa (AC) of renal crest or renal papilla
-vasa recta = take water passing through collecting & papillary ducts
papilla or renal crest = terminal portion of inner medulla = extends into renal pelvis or calices
Describe the vasculature.
-high blood supply (25%)
-terminal artery system
Renal -> interlobar artery -> arcuate artery-> interlobular artery -> intralobular (arcuate) artery
-afferent arteriole
> glomerus (capillaries)
-efferent arteriole
>peritubular capillaries (surround tubules)
>vasa recta (surrounds loop of henle)
-intralobular vein
-interlobular vein
-arcuate vein
Describe the interstitium.
-more present in inner medulla & sparse in cortex
-interstitial cells: fibroblasts, bone marrow derived, lipid laden interstitial cell (stellate shaped) in inner medulla mostly = produce prostaglandin E2
Describe lymphatics.
-found in interstitium surrounding intrarenal arteries
kidney has efferent innervation to the smooth muscle of arteries, afferent & efferent arterioles, & descending vasa recta
Describe the juxtaglomerular apparatus.
- DCT association with renal vasculature
What are the functions of the kidney?
- Water & electrolyte homeostasis
-filtration of cell waste from blood
-selective reabsorption of water & solutes
-regulation of fluid balance
-maintain electrolyte homeostasis/acid base balance - Excretion of toxic metabolite waste products & excess water
- Production of hormones = renin & erythropoietin endothelial cells of cortical peritubular capillaries (stimulates production of RBCs)
- Regulate BP = juxtaglomerular apparatus
- Activate endogenous Vit D (calcitriol, active form)
>skin - liver - kidney
Describe the JG apparatus.
1) macula densa = chemoreceptors that sense Na concentrations in filtrate (Na chemoreceptors)
2) modified smooth muscle = JG cells of afferent & efferent arteriole.
-Detect variations in BP (baroreceptors)
-secrete renin into vessel lumen in response to low Na in filtrate & low BP
Describe the JG apparatus & BP.
Labeled renal corpuscle picture.
What are the 4 layers of tubular organs?
- Mucosa
-lamina mucosa/epithelium
-LP
-lamina muscularis - Submucosa
- Muscularis
- Serosa/adventitia
NO lamina muscularis if 3 layers only
Describe the ureters.
-urine from renal pelvis to bladder
-tunica mucosa = urothelium (transitional epithelium) U
-tunica submucosa = LP
no lamina muscularis
-tunica muscularis M
>3 layers of smooth muscle
>outer & inner longitudinal
>middle circular layer
>autonomic innervation = peristalsis
-tunica adventitia
Describe the urinary bladder.
-tunica mucosa = urothelium
>LP
>lamina muscularis
-tunica submucosa
-tunica muscularis
>outer & inner longitudinal
>middle circular layer
*smooth muscle (detrusor muscle)
*skeletal muscle = sphincter near urethra
-tunica serosa/adventitia
Horse urinary bladder picture.
Glands in the horse (g)
Bulging cells of transitional epithelium. (Picture)
LPM = lamina propria mucosae
Male dog urethra & prostate. (Picture)
-urothelium proximal
-squamous distal
-accessory sex gland
-mucous glands
MALE:
-vascular stratum (corpus spongiosum)
-tunica muscularis/urethral sphincter
>smooth muscle proximal
>skeletal distal
FEMALE: shorter (more bacterial infection)
Describe renal development.
-pronephros - regresses in mammals
-mesonephros
>forms nephron that secrete fluid into amnion (regresses later)
>mesonephric duct (wolffian duct) = retained in males = forms Epididymus, vas deferens, seminal vesicles
- metanephros
Describe the metanephros.
- Ureteric bud - outgrowth of mesonephric duct
- Collecting tubules form, bifurcate = nephrons begin to develop
- Metanephros duct becomes ureter
urinary bladder & urethra are derived from endoderm
